SUBFAMILY CALLIPHORINAE 267 
F) with dorsal cornua rather widely separated from ventral. 
Anterior spiracles with a variable number of branches, more 
often with 7 or 8, these rather prominent, the portion external 
to euticle approximately equal in length to stigmatal chamber. 
Fuller (1932, p. 82) found the number of branches in the an- 
terior spiracles to be 10 in Australia, Patton and Evans (1929), 
10 to 11 in England, Knipling (1936, ». 283), 5 to 10 in North 
America. 
Pupa. The length of the pupal stage of Phaencia sericata 
varies from 3 to 5 days during July and August. Herms (1928) 
noted that 4 days were required for those individuals having the 
shortest larval feeding period and 7 days for those having the 
longest larval feeding period; and Wardle (1930) and Evans 
(1935a) recorded in some detail the effects of temperature and 
humidity upon the duration of the pupal period of this species. 
Roberts (1930) observed that puparia of sericata may be 
found in soil at a depth of approximately 114 inches, and Smith 
(1929) found that adults were able to emerge from puparia 
buried under 4 feet of loose soil. From depths of more than 3 
feet, 50 percent of the emerging flies reached the surface. 
Generations. According to Wardle (1930), there were four 
generations of Phaenicia sericata each year between May and 
October in the vicinity of St. Paul, Minn. There are probably 
aS many as eight toward the southern limits of the distribution 
of the species. 
Hibernation. Overwintering of serrcata is accomplished in the 
larval or prepupal stage in North America. According to Holda- 
way and Evans (1930), this species successfully overwinters 
principally as larvae; puparia formed during the fall months 
were mostly parasitized by Alysia manducator Panz. 
Adult. The preoviposition period probably lasts from 5 to 9 
days. 
Ovipositing females of sericata are attracted to media exposed 
to bright sunshine, although they actually oviposit upon the 
shaded portions of the medium’s surface. Oviposition usually 
occurs between the hours of 11 a. m. and 2 p. m. when the sun- 
shine is at its maximum intensity. 
This species is the first of an ecological succession of sapropha- 
gous insects to attack dead animals. Oviposition begins within 
a few hours after death of the animals. Fresh meat is attacked 
within a few minutes after exposure. 
Salt (1932) reported one female sericata that produced 1, 330 
eggs, while Mackerras (1933) recorded one which deposited 2,373 
eggs and another (a hybrid between sericata and cuprina) mitch 
